Question

Identify A, B, C and D in the silencing of RNA of the nematode, Meloidogyne incognita

• A. A: Ingestion of siRNA by nematode post infection
  B: Production of sense and antisense RNA
  C: siRNA cleaves or stops translation of target mRNA
  D: Agrobacterium transfers dsDNA into the plant
• B. A: Production of sense and antisense RNA
  B: Agrobacterium transfers dsDNA into the plant
  C: Ingestion of siRNA by nematode post infection
  D: siRNA cleaves or stops translation of target mRNA
  
• C. A: siRNA cleaves or stops translation of target mRNA
  B: Ingestion of siRNA by nematode post infection
  C: Production of sense and antisense RNA
  D: Agrobacterium transfers dsDNA into the plant
• D. A: Agrobacterium transfers dsDNA into the plant
  B: Production of sense and antisense RNA
  C: Ingestion of siRNA by nematode post infection
  D: siRNA cleaves or stops translation of target mRNA

Answer 1

The correct option is D A: Agrobacterium transfers dsDNA into the plant

B: Production of sense and antisense RNA
C: Ingestion of siRNA by nematode post infection
D: siRNA cleaves or stops translation of target mRNA
Nematodes cause severe damage to the major crops all over the world.

Meloidogyne incognita is a nematode which infects the roots of the tobacco plants and causes a great reduction in their yield.

To prevent this infestation, RNA interference technology is used.

It involves transfer of dsDNA of specific vital genes of the nematode into the tobacco plant using Ti plasmid.

The Ti (tumour inducing) plasmid from Agrobacterium tumefaciens is a natural vector of dicotyledonous plants. It causes tumours in the plants. This plasmid has been made harmless and is used to carry the double stranded DNA which will transcribe to make dsRNA. The dsRNA is cut by the dicer into shorter fragments of 20–25 nucleotides called siRNAs (small interfering RNA).

During infection, the nematode ingests the siRNAs using its stylet. These siRNAs are then taken up by the intestinal cells. These are then processed by the RNA induced silencing complex (RISC). The action of RISC leaves the single stranded RNA that pairs with the complementary sequence of target mRNA produced after transcription of target genes. Target mRNA is a specific nucleotide strand which is to be silenced to prevent the growth of the nematode. This inhibits further translation of the target mRNA.